The present invention relates to the joining of aluminium and titan components. In particular, the present invention relates to a component e.g. for an aircraft, and to a method for connecting a first region of a titanium material and a second region of an aluminium material for forming a component, for example for an airplane.
In the following, the field of the invention is further described with respect to material technology, processing technology and application technology:
Concerning Material Technology:
The thermal joining of different materials is published, since 1935, for example, in Holler, M.; Meier, H.: “Beitrag zu den Untersuchungen der Autogenverbindungen mit anderen Metallen”, Autogene Metallverarbeitung, 28, 1935, 12, pages 177-18, which hereby is incorporated by reference, such joining technologies mentioned in the literature mostly have a double nature, which means: for the low temperature melting materials, a welding process takes place, since they are melted-up. In these processes, the joining temperature is adjusted in such a way that for the joining partners which melt at higher temperatures, there takes place a soldering process. For the moment of joining, differing temperature conductivities, melting points and solubilities of the materials are of special importance. The substance-to-substance or integral connecting of the metals is effected by means of process related diffusion processes which are determined by temperature and time. In this context, in the connection region, there arise more or less pronounced inter-metallic phase borders. Many interesting matchings of alloys show great differences with respect to melting point and thermal conductivity, which can be problematic while joining by means of conventional welding procedures like WIG, MIG or E-Hand, and can lead to formation of cracks.
Concerning Processing Technology:
Dupak et al., Applications of a New Electron Beam Welding Technology in Vacuum Equipment Design 2000, which is hereby incorporated by reference, introduces an electron beam welding procedure, by means of which aluminium can be joined, for example, with copper, nickel, silver and steal. At first, the joint region is heated with a defocused laser beam as far as just below the melting temperature of the low temperature melting material. Afterwards, the low temperature melting material is melted-up by means of a focused laser beam, so that this can wet the material which melts at higher temperatures. The procedure is limited to rotationally symmetric components. In this way, Dupak intends to produce joints, which are mechanically resistant and are suitable for applications in the vacuum technology. Two successive electron beam joining processes are necessary one after another, in order to ensure a reliant joint between the materials. The expenditure of time and costs for the joining procedure is great.
N.N.: “Titan kann mit Aluminium verbunden werden. Nippon-Aluminium nimmt dunne Kupferlagen und ultraschallbehandeltes Lot”. Blick durch die Wirtschaft-insert of the Frankfurter Allgemeine Zeitung, vol. 36 (1993), booklet 150, p. 8, which is hereby incorporated by reference, describes a soldering method, which enables a production of sheet plates and formed parts of titanium and aluminium. During the process flow for the production of connections of such kind, copper plated titanium is applied. A zinc-aluminium solder is used as solder material. The solder is applied to the titanium and is temporarily subjected to an ultrasonic treatment. Subsequently, the aluminium part or sheet plate to be connected to is brought into close contact to the solder melted at the titanium-side. The connecting of both metals subsequently is effected by means of an anew ultrasonic heating-up.
Another procedure was disclosed in Suoda the “Creation of heterogenian weld joints of titanium and aluminium based materials by electron beam welding”, Welding science and technology; Japan, Slovak; Welding Symposium, Tatranske Matliare, 1996, S. 157-161, which is hereby incorporated by reference. The application of an electron beam welding is described in the context of this publication. It was the aim of the work of Suoda, by means of the application of the electron beam, to produce an Al—Ti mixed crystal instead of inter-metallic phases. At the same time, the electron beam is temporarily exclusively directed onto the boundary layer of the low-temperature melting aluminium, so that the titanium, which melts at a higher temperature, is dissolved in the melting film. The experiments were carried out at high-vacuum. However, the analysis of the weld seams showed that the aimed at target could not be achieved: cracks and inter-metallic phases emerged at the boundary surfaces.
Fuji, A.; Ameyama, K.; North, T. H.: “Influence of silicon in aluminium on the mechanical properties of titanium/aluminium friction joints.” In: Journal of Materials Science, 1995, volume 30, booklet 20, pages 5185-5191 and Fuji, A.; Kimura, M.; North, T. H.; Ameyama, K.; Aki, M.: “Mechanical properties of titanium-5083 aluminium alloy friction joints.” In: Materials Science and Technology, 1997, volume 13, booklet 8, pages 673-678, which are both hereby incorporated by reference, concern the compound Ti—Al, considering the effects caused by silicon on the friction welding with subsequent heat treatment. The ductility of the compound is deemed to suffer from the creation of TiAl3 in the phase transition. The creation of TiAl3 can be reduced by means of silicon fractions within the aluminium base-alloy. It is assumed that silicon separations act as a barrier for a diffusion process.
A further procedure, which is hereby incorporated by reference, was published in N.N: Department of Materials and Metallurgical Engineering: “Stability of interfaces in explosively-welded aluminium-Titanium laminates”, New Mexico Tech, Socorro, USA, Journal of Materials Science Letters 19, Pages 1533-1535. Here, aluminium and titanium were connected with each other by means of explosive welding, in order to develop applications for the lightweight construction.
Concerning Application Technology
The Boeing company employs rod-extruded titanium seat rails in ranges, in which added corrosion is located with seat rails made of aluminium. Such seat rails could also be manufactured by means of rod-extrusion technology or welding.
The solutions described above are believed to have the following disadvantages:
Concerning Processing Technology
Narrow process barriers (for example application only in the area of 1) sheet plates, 2) to linear, plane or rotationally symmetric components)
High process costs or manufacturing costs
Bad or no possibilities for repair welding
Concerning Application Technology
On the one hand, seat rails made of titanium solve the corrosion problem at seat rails made of aluminium, which causes high maintenance costs for the airlines. On the other hand, this solution is believed to have the disadvantage that the costs of acquisition and the component weight of these seat rails, as compared to seat rails made of aluminium, are considerably higher.